In known mobile radio systems, such as the GSM (Global System for Mobile Communications), each mobile station is assigned only one subscriber. Thus, each mobile station can only be used by a single subscriber. In the GSM, uniform bandwidths are fixed for the subscriber channels (see, for example, pages 195 to 203 of a book by M. Mouly and M.-B. Pautet entitled "The GSM", published by the authors in 1992, 49 rue Louise Bruneau, Palaiseau, France). For each subscriber channel, either a bandwidth of 25 kHz is made available in the so-called full-rate mode (with 8 TDMA channels in a 200-kHz band) or a bandwidth of 12.5 kHz is made available in the so-called half-rate mode (with 16 TDMA channels).
DE-OS 42 22 237, Hupperrich et al. discloses a mobile radio system for serving an area along a supply route, particularly along a railroad line. In that system, which is designed for many subscribers, a mobile station installed in a train is connectable via a directional radio link with base stations arranged along the railroad line. The system is a cellular system, so that different carrier frequencies must be provided for adjacent base stations, which necessitates complicated and costly radio network planning. In the mobile radio system, which is preferably designed according to the GSM standard, each mobile station is assigned only a single subscriber channel (TDMA time slot). How several subscriber channels can be made available simultaneously for the passengers on the train and for train control by radio is not described in DE-OS 42 22 237.